tolerances for the hardened properties of the trial batches shall conform to the requirements in Table 603.6.2.1C:
TABLE 603.6.2.1C Hardened Property Test Total # Specimens Specimen Size Age at Testing Magnitude of Loading Approval Condition Compressive Strength (AASHTO T 22) 7 4”x8” or 6”x12” cylinders 1 @ 24 ± 2 hrs. 1 @ 3days ± 2 hrs. 1 @ 7days ± 2 hrs. 1 @ 14days ± 2 hrs. 3 @ 28days ± 4 hrs. Load Until Failure per Design Modulus of Elasticityb (ASTM C469) 7 6”x12” cylinders 1 @ 3days ± 2 hrs. 1 @ 7days ± 2 hrs. 1 @ 14days ± 2 hrs. 3 @ 28days ± 4 hrs. 40% of compressive strength (obtained above) ≥ 57,000√f ' c a Creepb (ASTM C512) 8 total (3 loaded, 3 remain unloaded, 2 tested for compressive strength) 6”x12” cylinders 72 ± 2 hours at age of initial loading 40% of compressive strength at time of loading Creep Coefficient c ≤ 1.19 at 90 days a Length Change (ASTM C157) 3 3”x3”x11” prisms 56 days 28-day cure per ASTM C157 then Air Storage for 28 -days ≤ 0.0002 at 28 days of Air Storage a Rapid Chlorideb Permeability (AASHTO T 277) 3 4”x2” disc specimen 56 days or 28 days 60.0 ± 0.1 V ≤ 1500 coulombs (56 days) or ≤ 2000 coulombs (28 days) Freeze -Thaw Resistance (ASTM C666 - Procedure A)b 3 3”x4”x16” prisms 28 day cure prior to testing 300 cycles (0oF to 40oF) Durability Factor ≥ 80
Fabricator’s Engineer may submit calculations for prestress losses, camber, and long term deflections to the Division for review in accorda nce with Section 105.2.1.1, the Division Approval Method for shop drawings. If the Fabricator’s calculations show that the values exceeding the specified values in Table 603.6.2.1C will not adversely affect the prestress losses, camber, and long term defl ections, and the Division approves these calculations, then the ClassS -P mix in question may be used to fabricate prestressed bridge members.
and moist cured in the laboratory at a temperature between 73.5 ± 3.5 °F until the time of test. Freeze -Thaw Resistance testing shall begin when the specimens are at an age of 28 days.
of Initial Loading. The Initial Elastic Strain shall be determined within 2 minutes after the application of the initial load.
365 In addition to the hardened property tests above, at least one trial batch shall be subjected to the prestressing strand bond strength testing as outlined in MP 603.06.20. The ClassS -P mix in question must pass this test. Although a concrete mix may meet the necessary strength requirements and exhibit acceptable fr esh properties at the time of initial testing, the Engineer can require a re -design of the mix based on other criteria, such as insufficient retention of the slump flow for the mix, excessive foam buildup, etc. The slump flow of the mix must be retained, within the limits specified in Table 603.6.4.1, throughout the duration of the concrete placement. The submittal for a proposed mix design shall include completed copies of Attachments 1S -P, 2S-P and 3S -P of MP 711.03.23. All pertinent information suppor ting these attachments and pertaining to the information in them should also be submitted.
603.6.3-Proportioning of Normal (Non -SCC) Concrete: Materials shall be proportioned by weight, unless otherwise authorized by the Engineer. The concrete shall c ontain the minimum water -to-cementitious materials (w/c) ratio required to obtain satisfactory workability and the specified minimum strength, but in no case shall this (w/c) ratio exceed 0.44, including the free water in the aggregate and/or admixtures. The minimum cement factor shall be 658 lbs. per cubic yard. Concrete for all members shall be air -entrained with a target air content of seven percent (7%) . A working tolerance of plus or minus two percentage points will be allowed. When the ambient tem perature is 90°F or higher, a mix using a retarding admixture shall be used. Slump shall not exceed eight ( 8) inches with the use of high range water reducers.
603.6.3.1 -Proportioning of ClassS -P Concrete: The water -to-cementitious materials (w/c) rat io for ClassS -P concrete shall fall within a range of 0.32 to 0.40. A water -to- cementitious materials (w/c) ratio less than 0.32 may be used if approved by the Engineer. The minimum cementitious material factor for ClassS -P concrete shall be 658 lbs. p er cubic yard. Unless otherwise approved by the Engineer, the maximum cementitious material factor for ClassS -P concrete shall be 799 lbs. per cubic yard. Concrete for members cast with ClassS -P concrete shall be air -entrained with a target air content as shown in Table 603.6.2.1B . A working tolerance of plus or minus 1.5 percentage points will be allowed during fabrication. Material proportions should be selected to ensure an optimal combination of fresh and hardened properties. A standard ClassS -P concrete shall be designed to have a slump flow of 25 ± 2 inches in diameter. This twenty -five ( 25) inch slump flow diameter will be referred to as the target value for mix qualification and site approval. The contractor may request that the Engineer approve a different target slump, which must be less than twenty -five ( 25) inches. If approved, this requested value will be used as the target value for mix qualification and the approval of batches during production.
366 TABLE 603.6.3.1 Cementitious Materials Maximum Percent of Total Cementitious Materials in ClassS -P Concrete by Mass Class F Fly Ash 25 Slag Cement 50 Silica Fume 10 Total of Class F Fly Ash and Silica Fume 35 Total of Slag Cement and Silica Fume 50
NOTE: Class F Fly Ash shall constitute no more than 25 percent (25%) of the total weight of cementitious materials. Silica fume shall constitute no more than 10 percent (10%) of the total weight of cementitious materials.
603.6.4 -Sampling and Test Methods: Sampling Freshly Mixed Concrete AASHTO T 141 Slump of Hydraulic -Cement Concrete AASHTO T 119 Unit Weight and Yield of Concrete AASHTO T 121 Air Content of Freshly Mixed Concrete AASHTO T 152 or AASHTO T 196 Standard Practice for Making and Curing Concrete Test Specimens in the Field AASHTO R 100 Compressive Strength of Cylindrical Concrete Specimens AASHTO T 22 Temperature of Concrete ASTM C1064 Static Modulus of Elasticity and Poisson’s Ratio of Concrete in Compression ASTM C469 Fabricating Test Specimens with Self -Consolidating Concrete ASTM C1758 Slump -Flow of Self -Consolidating Concrete ASTM C1611 Passing Ability of Self -Consolidating Concrete using J -Ring ASTM C1621 Rapid Assessment of Static Segregation Resistance of Self- Consolidating Concrete Using Penetration Test ASTM C1712 Static Segregation of Self -Consolidating Concrete us ing Column Technique ASTM C1610 Standard Method of Test for Electrical Indication of Concrete’s Ability to Resist ChlorideIon Penetration AASHTO T 277 Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing ASTM C666 Standard Test Method for Creep of Concrete in Compression ASTM C512 Length Change (Drying Shrinkage) of Hardened Concrete ASTM C157 Standard Test Method for Microscopical Determination of Parameters of the Air -Void System in Hardened Concrete ASTM C457 Standard Method of Microscopical Determination of Air -Void Content MP 700.03.50
Cylinders shall be manipulated and cured by methods identical to those used in curing the concrete members.
367 Slump, Temperature, and Air Content tests shall be conducted on the first batch of concrete each day and every time that cylinders are fabricated. Slump, Temperature, and Air Content tests shall also be conducted whenever Quality Control Personnel or the Inspector see a variation in the mix. Unit Weight and Yield tests shall be conducted on the first batch of concrete each day and thereafter, as deemed necessary by Quality Control or Quality Assurance Personne l. The Fabricator's Quality Control Personnel shall maintain records of the beam number(s) into which each batch of concrete is placed.
603.6.4.1 -Acceptance Testing of ClassS -P Concrete: During production, ClassS -P concrete shall be tested to determine the air content, slump -flow, passing ability using the J-Ring, rapid segregatio n resistance, and temperature. All five of those tests shall be performed on at least the first three batches of concrete produced each day, and thereafter until satisfactory control is established. Satisfactory control is established when all the results of three consecutive sets of tests meet the performance criteria in Table 603.6.4.1, without any mix adjustments. Once satisfactory control is established, the testing frequency may be reduced to one set of tests for each member cast in a form that day. If any mix adjustments are required or performed, testing shall continue until three consecutive sets of tests meet the performance criteria without any mix adjustments. Unit Weight and Yield tests shall be conducted on the first batch of concrete each day and thereafter, as deemed necessary by the Quality Control or Quality Assurance Personnel. The fresh concrete properties shall meet performance criteria as shown in Table 603.6.4.1.
TABLE 603.6.4.1 Fresh Property Production Acceptance Criteria Air Content (ASTM C173) Target ±1.5% Consistency (ASTM C1611) Target Spread ± 2.0 inches 2 seconds ≤ Measured T 50 ≤ 7 seconds Visual Stability Index ≤ 1.0 Passing Ability (ASTM C1621) J-Ring Value ≤ 1.5 inch Rapid Segregation Resistance (ASTM C1712) Penetration Depth (PD) ≤ 0.5 inch Temperature < 90°F Unit Weight and Yield ± 2.0% of Theoretical
603.6.5 -Strength of Concrete: Each strength test (i.e. strand release and 28 -day) shall consist of the average strength of a minimum of two compressive strength test cylinders fabricated from a single randomly selected batch of concrete, as it is being placed in the forms. A mini mum of one set of cylinders shall be fabricated (at random) for each member cast in a form, with a maximum of one set of cylinders per batch of concrete. These cylinders, molded during fabrication, shall be the same size specimens as were used in the appro ved mix design. Any member, for which the average concrete compressive strength at 28 -days is less than the 28 -day design compressive strength value, may be rejected at the option of the Contractor. If the Contractor elects to use such a member, it wil l be evaluated as to its adequacy for the use intended. Any member evaluated as unsatisfactory will be rejected by the Division, and the Contractor shall fabricate another member to replace the one which was evaluated as unsatisfactory. When the evaluati on indicates that the member will be satisfactory for its
368 intended use, the Engineer will provide for an appropriate price adjustment under the provisions of subsection 603.14.2.1. Whenever the compressive strength of a member at 28 -days is less than the 28-day design compressive strength value, the subject member may still be accepted without a price adjustment if the compressive strength at any time prior to shipment (up to a maximum of 56 - days from the date of fabrication) exceeds the 28 -day design com pressive strength value. The Division shall not be responsible for any project delays incurred due to the delayed strength attainment, and time extensions under Section 108 of the Specifications are not applicable to this scenario.
603.6.6 -Batching and Mixing: Concrete batching plants and their operation shall be in conformance with ASTM C94, “Specifications for Ready -Mix Concrete”. Concrete batch plants shall be capable of producing concrete of the quality required and they shall be adequa tely equipped and properly operated. Concrete supplied to the plant by an outside batch plant shall meet the same requirements of batch plant facilities. Evidence of conformance will be certification of the outside plant by the National Ready -Mix Concrete Association (NRMCA). Fine and coarse aggregates and cement shall be measured by weight. Water and liquid admixture may be measured by either weight or volume. Measurement of the various components of concrete, and measuring equipment shall be in accorda nce with ASTM C94. Concrete shall be mixed by one of the following methods:
the casting area by appropriate methods.
completely and delivered to the casting site in a truck mixer.
delivered to the casting site.
Mixing times shall be established by u niformity tests in accordance with procedures in ASTM C94. ClassS -P concrete shall be batched at the site of fabrication of the prestressed members. For ClassS -P concrete, all wash water must be completely discharged from the mixing drum prior to add ition of any materials for the subsequent batch. When using ClassS -P concrete, under no circumstances shall water be used to adjust the consistency of the mix. If it is necessary to adjust the ClassS -P concrete’s consistency, this shall be done through the addition of chemical admixtures only, and adequate mixing after the adjustment, must occur before any ClassS -P concrete is discharged into the formwork. Two compressive strength specimens, from this adjusted batch, shall be fabricated and tested. A lso, the concrete tests required in Table 603.6.4.1, with the exception of the unit weight and yield tests, shall be performed on this adjusted batch. These results must meet the requirements shown in Table 603.6.4.1.
603.6.7 -Placing Concrete: Suita ble means shall be used for placing concrete without segregation. The concrete mixture shall not be dropped from a distance of more than four (4) feet, relative to the top of the form or the reinforcement. Special care shall be taken to deposit the concret e in its final position in each part of the form. Working of flowing concrete along the forms from the point of deposit will not be permitted. Care must be taken to work the concrete under and around the prestressing strands and reinforcement. The plastic concrete shall be consolidated in place by either external or internal vibration, or both when necessary.
369 The vibrators shall be of a type and design approved by the Engineer, and the size of the vibrating head will be governed by the spacing of the prestr essing cables and reinforcement. Vibrators may be used only to consolidate the concrete after it has been properly placed. Internal vibrators shall be operated vertically and shall be slowly pushed into and pulled out of the concrete and shall not be hel d in one spot long enough to cause segregation. Concrete segregated by the vibrator shall be removed and discarded. Partially hardened layers of concrete shall not be penetrated or disturbed by the vibrator. Transmission of vibration into prestressing cabl e or reinforcement embedded in partially hardened concrete by the vibrating equipment will not be permitted. The plans for delivery and placement of ClassS -P concrete to the casting beds should ensure that construction of the entire member is completed during the workable period of the concrete established in MP 711.03.23, such that no vibration of the concrete is necessary at any point during construction. If vibration is to be used at any time during fabrication, the ClassS -P concrete mix a nd the method of construction must be pre -qualified as outlined in by the manufacturer such that there is a reasonably continuous feed into the formwork and, therefore, at no time shall there be a large pause or delay in the casting process which causes the fresh concrete properties to exceed the limits set forth in Table 603.6.4.1.
603.6.8 -Cold Weather Production: In addition to the requirements of Subsectio n 601.9.1, the following requirements shall apply to outdoor casting operations. When ambient temperatures below 40° F are anticipated, the following shall be used as necessary to keep the temperature of concrete within the prescribed limits:
temperature of these facilities are below 40º F, steam heat or other means shall be provided to maintain the temperature to at lea st 50° F unless concrete is delivered above 60º F and no frost, snow or ice is present in the form.
ice.
603.6.9 -Hot Weather Production: In addition to the requirements of Subsection 601.9.2, the following requirements shall apply to outdoor casting operations: When the ambient temperature is above 100 F, or other adverse weather conditions are present, it is recognized that plastic shrinkage of concrete, or loss of strength below specification requirements, or both may occur. If such conditions do occur, the following procedures or combination of proceduress hall be used as necessary to correct these deficiencies:
direct sunlight can be misted for cooling prior to placement of concrete.